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Found 9 results

  1. Hi guys, I'm kinda new to this software and this is my first post, after several days of trying to solve this problem: Am trying to simulation how stellar wind affects the gas clouds in interstellar space. https://www.spacetelescope.org/images/potw1106a/ (reference picture from Hubble) When new stars are born in high density regions, the ignition and radiation of these stars create winds that pushes the dust around them, sculpting away the surrounding molecular cloud. These winds can reveal this hidden star formation process and sometimes accelerate it, when this expansion compress another high density spots, this slowly collapsing cloud will form a new star. These places are also called stellar nurseries. So, i'm trying to visualice is the first parts of this process, the way stellar wind sculpts and reveal the clouds around them. I've modeled a random cloud to represent the very uneven density distribution. Where i'm having problem is in getting this "wind" to affect more the lowest density regions. I tried with a couple of fan forces in oposite directions and kinda worked, but could not get to work a mask using the density field, maybe is posible, but i couldn't do it. Then i tried a gas field wrangle to get a another velocity field "wind", from the origin and multiply it by a factor inverse to the density squared (see screenshot) This also kinda worked, but i get a very voxely looking render (video attached), maybe with a higher resolution and some blurring node somewhere could improve this. I also would like to achieve the effect that the winds is slowly expanding trough space (since the spatial scales here are huge), maybe i could bound it to an expanding sphere? (i dont like that the wind effect is instantaneous in all the scene) maybe some kind of raycast could be an option? i'm open to ideas, coz i don't even know how to begin to google that :/ That's what i've tried so far, would be really happy if someone could share some ideas or resources! Thanks in advance. pd1: another idea i would love to implement is to fake the dust colapse by gravity with some clumping also based on density (i tried with gasshred and gas surface tension with poor results) pd2: Eventually, i would like to get this expansion and subsequent peripheral density increase around to spark the birth of new stars. I don't know if is posible to create fuel from a certain density threshold or something like that. But that's a second post i guess. StarDust_07.hip StellarWind_Advect2_1.mp4
  2. I'm making an effect very much like this one from Entagma: https://vimeo.com/194277211 I've adjusted it a little and I noticed that some of the curves that get created collapse onto each other. I think it even happens at the very first frame. You can see that by the white parts of the lines. Those are the last created points. When two white parts meet, it means the curves collapsed and continues as 1 curve. What the setup does is it has a bunch of points as the active searching points. Each of these find target points in front of them and saves those in an array. Then a random point from within the array gets chosen and used to make the polywire. Sometimes, mainly at the very beginning, the searching points are close enough together so that they might find the same target points. This is where I believe the issue lies. What I would like to achieve is that I can check between the arrays on each of the points to see if they have similar target points and if so, remove those from one of the arrays. Or that when points get targeted by one searching point, they instantly get marked so that they can't be found again before the end of the timestep/solve. At this moment, I'm still trying to figure that one out. Any tips for this are much appreciated. Eckhart ObjectMaterialize.v005_00.hip
  3. Vacuum space explosion

    Hallo! I'm trying to figure out how to properly do space explosion / impact on mars or any other planet that has no atmosphere. I've read huge topic about smoke behavior: http://forums.odforce.net/topic/18397-get-rid-of-mushroom-effect-in-explosion-and-add-details-in-the-opening/ So let's begin from simple things. REFERENCE: so behavior of dust/particles is... super simple. About like this: Ans this behavior is everything I can't achieve with smokesolver. Maybe I'm idiot. Test of explosion: 1. microsolver "projectmultigrid": When I turn off this microsolver it actually does what I'm trying to achive: no mushrooms because of no pressure. Thing is, I'm trying to somehow control gradient between on/off. Because velocity is not expanding. And there are a lot of artifacts. Mushrooms in explosions are the effect of the pressure (from what I understand), and as it's wrote in large Jeff post (in link above) : divergence field. But because I'm working right now on smoke solver only : it does not have this field (no combustion model). So main question is (probably): where should I control pressure. Or disable it? I've modified it on the dop level, with gasvop with pressure subtracted from itself, mult by 0 - but it did not had any effect (both presolve and postsolve). I assume it calculates this vel somewhere in between (?). I must be doing something wrong. 2. How to make smoke just keep going without twirls and all of that "nice stuff". Just inital vel, that's it. Imagine super simple sphere, default pyro, all off, only vel up. What I've tried: - somehow remove pressure (not sure I've done this right, but I could delete temperature, vel, density... but pressure without any luck) - advect vel field itself (no difference in vel = no pressure), but that lead to uncontrolled vel turbulence, when used with more complex emitter. - somehow blurring vel field and adding it when projectmultigrid was off to expand smoke. - make those red particles a volume and to look like smoke, but there is problem with disappearing (they kind of always pop out of existence even if particles fade nice and slow). Some tests: advecting smoke only with "pipevel" , again projectmultigrid off (no mushrooms = good)
  4. Asteroid Dust Trails

    Hey guys, This is my first post here! I'm new to Houdini and learning a lot from the shelf tools, available tutorials, forum posts and documentation. Now I'd like to create dust trails from shattered asteroid pieces. Here is what my trail setup looks like so far (.hip attached): I'm almost happy but a few things should be improved/fixed: The "Source Volume" node doesn't know the torus' velocity when drawing into the density field, which results in stepping. I'd like the smoke to interact with (flow around) the geometry. Can I draw it into an obstacle and/or velocity field? Merging the solvers didn't help yet. Maybe I could modify the air pressure/resistance aroudn the asteroid and ignore it for the smoke that's far enough away? With the "Gas Resize Fluid Dynamic" node active, there's some strange aliasing happening towards the end. Any tips on how to achieve/fix those issues would be great! I've been searching the forums and several tutorials already. But as today most of them are not written text but videos instead, it's hard or at least very time-consuming to find specific information. I'll keep playing with nodes and parameters, watching volume wrangling tutorials and also try preparing an upres setup. Thanks! Hebi 2016-08-04_asteroid_trail_v002.hip
  5. Space Challenges | Ad

    One of the recent CG ads my team at BlueLake created, where Houdini was used to do FX and some geometry magic. Project was done for the spaceedu.net Concept art: Final: Cheers, Tom
  6. Shading Fractal Shapes

    Hello everyone, does anyone know how can I shade a fractal shape like this on the picture with houdini mantra?? Thank you.
  7. Hey Guys, Been having a lot of fun making a cool video with some friends and starting some cool things! We just released the teaser this morning ( a long night for my friend ). I did some work in Houdini for the opening title ( its in the teaser ) and some other treats that are to come! We are releasing next week and I will be posting some of the work and breakdowns here! For now here is the link to the teaser and a still some the opening shot! Check out the pages on the youtube description! More to come so thanks for watching! https://www.youtube.com/watch?v=i-PIwXNAPCE
  8. Normal Map for Mantra Surface Shader

    I don't know why, but I've never successfully been able to import a normal map into houdini from zbrush or mudbox. I've had this issue for a year now, and I always just do bump instead. It works, but I'd rather have a tangent space normal map. Both tangent space and object space appear to screw up the lighting in Houdini renders. I'm using the mantra surface shader, default with houdini 13. Anyone know how to get this to work without the harsh edges on the shadows? Image 1 shows how the object looks with a normal map plugged in Image 2 shows how the object looks with "normal" selected from the drop down menu without the map being checked on. Image 3 shows how it looks without the normal option being selected from the drop down menu, just regular obj, no maps. Image 4 shows what I mean by "drop down menu" This is not the problem with the obj or the maps. They work fine in maya. Something weird is happening in Houdini. Thanks!!!
  9. Tangent normal maps

    Hello everyone, I am trying to apply some normal maps in tangent space to some models. I used both Zbrush and xNormal for exporting the normals, none of them work. As far as I understand it, there are two types of normal maps, tangent and object space. Since the geometry will be deformed, I am using NM in tangent space. I wanted to use the default mantra surface model first, to see how it works, but it doesn't work in the first place. It basically takes in a normal map and then uses the convertNormal subnetwork (posted below). The some of the channels still seem flipped. I tried flipping other channels using the multiply node, but it simply does not work. I have tried looking it up, and there are some pretty ancient threats. One of them also provides an example file, but it seems houdini changed a bit since then. http://www.sidefx.com/exchange/info.php?fileid=561&versionid=561 The VEX function vop_computeTangents($tanU, $tanV, normalize(N), $uv, 2); does not expect the same input anymore. I haven't really worked with VEX code yet, so I am a bit stranded here. Isn't there a fast way to set tanget space normal maps up? I can't believe such a simple thing is so hard to set up. Do I need to flip certain channels when I export the NM? Am I overlooking something, or am I just really stupid? Any kind of help or information is welcome Thanks a lot Sustaxa
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